In this study, the effect of a drug that suppresses the immune system was studied on children who received a human autopsy valve at the time of surgery for repair of a congenital heart defect. To do this, one-half of the children received this medication and the other one-half did not. Blood samples were drawn on all children 1 week, 1 month, and 3 months after surgery and the immune response of the children to the human autopsy valve was measured. Heart ultrasound tests were obtained to see whether there was any difference between the 2 groups with regard to valve function. No difference was found between groups with regard to the immune response or valve function.